Changes in the Composition of Raw Tea Leaves from the Korean Yabukida Plant during High-Temperature Processing to Pan-Fried Kamairi-Cha Green Tea

• Published in: Journal of food science Vol. 74; no. 5; pp. C406 - C412
• Main Authors: Friedman, Mendel, Levin, Carol E, Choi, Suk-Hyun, Lee, Seung-Un, Kozukue, Nobuyuki
• Format: Journal Article
• Language: English
• Published: Malden, USA Blackwell Publishing Inc 01.06.2009; Wiley; Wiley Subscription Services, Inc
• Subjects: Alkaloids - analysis; beverage industry; Biological and medical sciences; caffeine; Caffeine - analysis; Camellia sinensis var. sinensis; catechin; Catechin - analysis; chlorophyll; Chlorophyll - analysis; Chromatography; Chromatography, High Pressure Liquid; Coffee, tea and other stimulative beverage industries; cultivars; Enzymes; flavor; Food Handling - methods; Food industries; food nutrient losses; food processing; Food science; frying; Fundamental and applied biological sciences. Psychology; Glutamates - analysis; green tea; High temperature; Hot Temperature; Kamairi-cha; Korea; leaves; pan-fried; pan-frying; pan-heating; Plant Leaves - chemistry; raw green tea leaves; roasting; rolling; sweet tea; sweetness; Tea; tea (beverage); Tea - chemistry; temperature; theanine; Water - analysis; water activity; water content; South Korea; Japan; Korea; Flavanol; pan-fried; Catechin; Plant leaf; High temperature; Flavonoid; tea; Polyphenol; Plant part; theanine; Kamairi-cha; Chemical composition; Green tea
• ISSN: 0022-1147; 1750-3841
• DOI: 10.1111/j.1750-3841.2009.01185.x

To develop a better understanding of compositional changes occurring during the production of commercial teas, we determined by high-performance liquid chromatography (HPLC) changes in ingredient levels during each of several manufacturing steps used to produce Kamairi-cha, a premium green tea. Kamairi-cha uses pan-frying instead of the usual blanching technique to inactivate the enzymes responsible for producing traditional black tea. The resulting tea lacks the characteristic bitterness of green tea, producing a green tea that is described as sweet tasting. The processing steps used to produce this pan-fried tea were as follows: 1st roasting, 1st rolling, 2nd roasting, 2nd rolling, 1st firing, and 2nd firing. The results show that during production at temperatures up to 300 °C, raw leaves lost (in percent) 97.3 water, 94 two chlorophylls, 14.3 seven catechins, and 2.75 caffeine. A separate analysis showed that the final product contained 21.67 mg/g dry wt of the biologically active amino acid theanine. The results of this 1st report on changes in individual catechins and other tea ingredients in tea leaves during pan-frying make it possible to select production conditions that maximize levels of beneficial tea ingredients. The possible significance of the results for the human diet is discussed.